1. The Field Of The Invention
The present invention relates to improved devices for forming an environmental tight seal on the free ends of cables, conduits and the like.
2. The Prior Art
It is often quite desirable to be able to form an environmental tight seal on the end of a cable, conduit or the like. For example, when electrical lines are initially run, there may be a delay before the final termination or joining of the cable is effected. It is clearly desirable to have such a cable protected from destruction by exposure to the elements by sealing any free ends. However, it is also desirable that any sealing device should have the capability of being readily applied, regardless of the environmental considerations, and likewise be readily removable without leaving any undesired residues or defects in the exterior layer of the cable. It is also desirable to have a sealing device that is not destroyed when it is removed so that it can be repeatedly used, thus providing a long service life.
One well known method for providing a seal is to use a member which is formed of a thermo-plastic material. The member is expanded by the application of heat, positioned over the cable end and allowed to cool and contract to form a tight seal. Sometimes this type of seal may be removed by reheating until it expands again. However, sometimes reheating is not possible because of environmental considerations and the seal must be destroyed to be removed. This type of seal cannot always be used, for example, in an environment filled with explosive gases because it would not be possible to use heat without extreme danger. These thermo-plastic seals also have a very limited life.
Another well known method for sealing a free cable end is to dip the cable end into a molten bath of sealing material which, when hardened, seals the cable end. However, this type of seal is very difficult to remove and thus has only limited applications.
Another known seal for the free end of cables is shown in U.S. Pat. No. 2,145,705. This seal is similar to a bicycle handle-bar grip, such as the one shown in U.S. Pat. No. 2,618,986 and is simply rolled onto the cable end. This type of seal has two primary disadvantages. First it is rather difficult and expensive to apply since the cylindrical sidewalls must first be rolled up. Secondly, the device is usable for only a limited range of diameters of cables.
A further known cable end seal is represented by Australian Pat. No. 225,745. The cover shown in this patent provides a tight seal on the free end of a cable. However, this seal would be very hard to apply since a tool must be used to open the cover. The cable is inserted while the cover is held open by the tool. The tool is then withdrawn allowing the cover to tightly engage the cable.